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3 years ago

List two observations that could be evidence of a chemical reaction.

Chemistry

2 answers:

solmaris [256]3 years ago

8 0

Answer:

Emission of heat or light, or a color change.

Aleks [24]3 years ago

7 0

Answer:

1) Smell or odour

2) Colour change

Explanation:

1) Smell or odour

Example: Add HCl to a FeS solution. There will be a strong odor of H2S

2) Colour change

Example : NaOH and KMnO4 solution to a river water sample. There will be a colour change to brown.

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Does uranium or barium nucleus have a stronger net force holding its protons

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3 years ago

How much would the boiling point of water increase if 4 mol of sugar were added to 1 kg of water (Kb = 0.51°C/(mol/kg) for water

andre [41]

Answer : The boiling point of water increases, $2.04^oC$

Solution : Given,

Moles of solute (sugar) = 4 moles

Mass of solvent (water) = 1 Kg

$K_b=0.51Kg^oC/mole$

i = 1 for sugar

Formula used :

$\Delta T_b=i\times K_b\times m\\\Delta T_b=i\times K_b\times \frac{n_{solute}}{w_{solvent}}$

Where,

$\Delta T_b$ = elevation in boiling point

$K_b$ = elevation constant

m = molality

$n_{solute}$ = moles of solute (sugar)

$w_{solvent}$ = mass of solvent (water)

i = van't Hoff factor

Now put all the given values in this formula, we get the elevation in boiling point of water.

$\Delta T_b=(1)\times (0.51Kg^oC/mole)\times \frac{4moles}{1Kg}=2.046^oC$

Therefore, the elevation in boiling point of water is $2.04^oC$

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4 years ago

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What is the mass of 22.4 L of H2O at STP?

lord [1]

The mass of 22.4 L of H2O at STP IS 18.0 grams

calculation

mass = moles x molar mas
Calculate the moles of water at STP

At STP 1 mole =22.4 L
what about 22.4 l of H2O

by cross multiplication

1mole x22.4 L/22.4 L = 1 mole

molar mass of water = (1 x2) + 16 =18 g/mol

moles is therefore = 8 g/mol x 1 mol = 18 grams

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3 years ago